KIT and mucosal melanoma: Approximately 15%–20% of cases of acral and mucosal melanoma will harbor an activating mutation in KIT. The tyrosine kinase inhibitor imatinib has been shown to increase PFS, with an overall disease control rate of approximately 55% when studied in small clinical trials and remains an option for patients who progress while on or are ineligible for immunotherapy and harbor a KIT mutation (38).